(1) Field of the Invention
The present invention relates to a high frequency device module in which a high frequency device such as a micro wave device is buried and more particularly to a structure of the same.
(2) Description of the Invention
Demands for increase of transmission capacity have been intensified more and more with a progress of information society in recent years, so that a system having a larger transmission capacity and a higher level modulation system have been demanded. Accompanied by this, devices having a high gain and produced at an inexpensive cost have been requested.
To meet such demands, a module disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-345419 is known. In the module, a simple package in which a single sheet of ceramic has a metal plate and a device is fixed thereon is coated with polyimide so as to protect the surface and potting material for protecting wire and the device is applied thereon.
However, although the potting material has insulation property, if a high performance device or a high gain device is used, electromagnetic field is radiated thereby affecting the environment or its performance is deteriorated extremely by incoming of surrounding electromagnetic field or output of microwave emitted from itself. For the reason, application field of this high frequency device module is sometimes confined.
Further, Japanese Patent Application Laid-Open No. 2003-298004 has disclosed a high frequency device module sealed with insulating resin by dispersing metallic particles such as Ni particles in order to prevent an interference of electromagnetic wave between active device chips which operate in a high frequency band.
However, in a case where such a high frequency device module is used, there is a possibility that its metallic particles may corrode and a problem that sufficient electromagnetic shielding cannot be achieved in a long period.